This reporting year 91 patient visits were accomplished in fulfillment of the ongoing need to develop, modify and validate new hardware and software dedicated to the study of human auditory function. These values are essential as upgraded hardware and software becomes available and new normative data must be developed as a prerequisite to clinical research applications. This fiscal year new dedicated equipment is in use including: auditory evoked potential and cochlear emissions hardware; and upgraded software for multi-frequency immittance and other microprocessor based instrumentation. Thus, new normative data is being generated in auditory evoked potentials for absolute and interpeak datapoints using both circumaural and insert earphones. These data are gathered and analyzed for ages 2 through 50 and by decade from 50 to 80. Currently, normative data for age groups below two, or above 50 are not yet complete. The subset of studies on cochlear emissions in this protocol has gained considerable momentum in this reporting period. The Clinical Auditory Unit of the NIDCD has been one of a select few audiologic facilities to have access at this time to experimental software for the study of distortion product otoacoustic emmisions (DPOE). In addition, we have recently acquired the only commercially available clinical instrumentation for DPOE's We now are in the position of being able to compare two approaches to the study of cochlear integrity. Current work includes studying the following: the repeatability of DPOE measures; the influence of ear canal resonance on the amplitude of evoked otoacoustic emmisions (EOE)s in normals; the influence of ear canal volume on the frequency responses of EOE's in normals and the comparison of spontaneous otacoustic emission in normals using two different acquisition paradigms. In addition, we now have click evoked emissions data on Waardenburg patients and some first degree relatives; patients with iron overload conditions and patients with Type 2 Neurofibromatosis. Plans call for evaluation of these data in FY '93. Multi-frequency typmanometry (MUFTY) continues to be an important part of our data collection activities, especially in the development of new norms with upgraded software. This year's effort has focused on collecting data necessary to establish resonance characteristics of the middle ear in normals and studying intersubject variability as a function of ear canal volume in subjects ages 18 through 50. We anticipate that the resonance characteristic of the middle ear, as measured by this procedure, will have specific and pertinent effects on evoked otoacoustic emissions. This effort will continue into FY '93 in order to include MUFTY data on normal healthy aging volunteers from ages 50 to 80 and in order to study other pertinent variables.